At present, our best tangible evidence for the presence of Ivory-billed
Woodpeckers along the Choctawhatchee River is recordings of double
knocks and kent calls. Instead of drumming like all other
woodpeckers that breed in the Southeastern U.S. Ivory-billed
Woodpeckers rap on trees with their bills twice in quick
succession. These sounds are called double knocks and the
ivorybill is the only bird in North America that gives such
displays. Our recordings are available for listening on Dan Mennill's Ivory-billed
Woodpecker Webpage.

The vocalization of Ivory-billed Woodpeckers is a brief nasally sound
that is most often written as “kent”. These kent vocalizations
are very distinct from the sounds of any other woodpecker in the
Southeastern U.S. and distinct from the sounds of most other animals of
southern swamps. Blue Jays and both White-breasted and
Red-breasted Nuthatches can make ivorybill-like sounds, as can Gray
Squirrels.

Between January 5 and April 23, 2006, Dan and Kyle made 11,419 hours of
audio recordings with seven listening stations. These stations
were spaced about 500 meters apart across our study site. As of
August 13, 2006 , Dan’s crew has searched all 11,419 hours for double
knocks
and kent calls and they’ve found 99 putative double knocks and 210
putative kent calls. These are the number of double knocks and
kent calls that Dan, Kyle, Brian, Tyler, and Geoff think cannot be
attributed to any known animal in the Choctawhatchee River Basin and
that sound most like the descriptions or recordings of Ivory-billed
Woodpecker vocalizations and knocks. The microphones used to
record these sounds are omnidirectional—record sounds from all
directions—which is necessary when recording sounds from a source that
can be anywhere around a microphone, but our use of omnidirectional
mics means that many of the recordings are faint. These sounds
cannot be readily attributed to any animal of the Florida panhandle
except Ivory-billed Woodpeckers. See Dan Mennill's Ivory-billed
Woodpecker Webpage for a detailed treatment of sounds and to listen
to all of the putative ivorybill sounds that we have recorded.

Perhaps the most compelling aspect of our sound recordings is that on
ten days we recorded multiple kent calls and double knocks at the same
listening station or at adjacent listening stations separated by 500
meters. One could perhaps dismiss our recorded kent calls as
atypical vocalizations of Blue Jays although Blue Jays were absent from
all but the edge of our study site throughout the winter and members of
our search team have yet to hear Blue Jays make sounds like our
putative kent calls. Moreover, typical Blue Jay sounds are never
recorded in association with these kent calls. Because jays
are vocal birds, it is unlikely that our kent recordings can be
attributed to Blue Jays silently approaching a microphone, giving one
or a few kent notes, and then slipping silently away. Likewise,
double knocks could be atypical drum patterns of Pileated Woodpeckers,
but such pileated double knocks must be rare because there is no
mention of such pileated double knocks in the literature, and no
members of our search team have heard pileateds make such double knocks
along the Choctawhatchee or anywhere else in the southern
forests. What are the chances that rare Blue Jay kent calls and
rare pileated double knocks would occur together in the same spot on
ten separate days of recording? It seems to us that a knocking and
vocalizing Ivory-billed Woodpecker as the source of the kents and
double knocks is the simpler explanation, especially when the location
of the sound recording is where 13 sightings were made and there are
many scaled trees and large cavities.

All information on this
website is
copyright Geoffrey Hill and Daniel Mennill.
No information on this page may used without explicit permission
(ghillATacesagDOTauburnDOTedu or
dmennillATuwindsorDOTca).